Add backoff_factor in connection to configure retry interval

Author: root

CHANGES.txt

@@ -5,6 +5,8 @@ Changes for crate
 Unreleased
 ==========
 
+- Added ``backoff_factor`` in connection to configure retry interval.
+
 - Added official Python 3.8 support.
 
 - Made it so that the SQLAlchemy dialect is now aware of the return type of the

docs/connect.txt

@@ -169,6 +169,18 @@ the optional ``error_trace`` argument to ``True``, like so::
 
 .. _authentication:
 
+Backoff Factor
+..............
+
+When attempting to make a request, the connection can be configured so that
+retries are made in increasing time intervals. This can be configured like so::
+
+    >>> connection = client.connect(..., backoff_factor=0.1)
+
+If ``backoff_factor``is set to 0.1, then the delay between retries will be 0.0,
+0.1, 0.2, 0.4 etc. The maximum backoff factor cannot exceed 120 seconds and by
+default its value is 0.
+
 Authentication
 ==============
 

src/crate/client/connection.py

@@ -28,7 +28,7 @@
 
 class Connection(object):
 
-    def __init__(self, servers=None, timeout=None, client=None,
+    def __init__(self, servers=None, timeout=None, backoff_factor=0, client=None,
                  verify_ssl_cert=False, ca_cert=None, error_trace=False,
                  cert_file=None, key_file=None, username=None, password=None,
                  schema=None):
@@ -37,6 +37,7 @@ def __init__(self, servers=None, timeout=None, client=None,
         else:
             self.client = Client(servers,
                                  timeout=timeout,
+                                 backoff_factor=backoff_factor,
                                  verify_ssl_cert=verify_ssl_cert,
                                  ca_cert=ca_cert,
                                  error_trace=error_trace,
@@ -103,6 +104,7 @@ def __exit__(self, *excs):
 
 def connect(servers=None,
             timeout=None,
+            backoff_factor=0,
             client=None,
             verify_ssl_cert=False,
             ca_cert=None,
@@ -140,12 +142,15 @@ def connect(servers=None,
         the username in the database.
     :param password:
         the password of the user in the database.
-
+    :param backoff_factor:
+        (optional)
+        define the retry interval for unreachable servers in seconds
     >>> connect(['host1:4200', 'host2:4200'])
     <Connection <Client ['http://host1:4200', 'http://host2:4200']>>
     """
     return Connection(servers=servers,
                       timeout=timeout,
+                      backoff_factor=backoff_factor,
                       client=client,
                       verify_ssl_cert=verify_ssl_cert,
                       ca_cert=ca_cert,

src/crate/client/http.py

@@ -101,6 +101,7 @@ def request(self,
                 username=None,
                 password=None,
                 schema=None,
+                backoff_factor=0,
                 **kwargs):
         """Send a request
 
@@ -130,7 +131,7 @@ def request(self,
         headers['Content-Type'] = 'application/json'
         kwargs['assert_same_host'] = False
         kwargs['redirect'] = False
-        kwargs['retries'] = Retry(read=0)
+        kwargs['retries'] = Retry(read=0, backoff_factor=backoff_factor)
         return self.pool.urlopen(
             method,
             path,
@@ -274,6 +275,7 @@ class Client(object):
     def __init__(self,
                  servers=None,
                  timeout=None,
+                 backoff_factor=0,
                  verify_ssl_cert=False,
                  ca_cert=None,
                  error_trace=False,
@@ -290,6 +292,7 @@ def __init__(self,
         self._inactive_servers = []
         pool_kw = _pool_kw_args(verify_ssl_cert, ca_cert, cert_file, key_file)
         pool_kw['timeout'] = timeout
+        self.backoff_factor = backoff_factor
         self.server_pool = {}
         self._update_server_pool(servers, **pool_kw)
         self._pool_kw = pool_kw
@@ -403,7 +406,14 @@ def _request(self, method, path, server=None, **kwargs):
             next_server = server or self._get_server()
             try:
                 response = self.server_pool[next_server].request(
-                    method, path, username=self.username, password=self.password, schema=self.schema, **kwargs)
+                    method,
+                    path,
+                    username=self.username,
+                    password=self.password,
+                    backoff_factor=self.backoff_factor,
+                    schema=self.schema,
+                    **kwargs
+                )
                 redirect_location = response.get_redirect_location()
                 if redirect_location and 300 <= response.status <= 308:
                     redirect_server = _server_url(redirect_location)